Many electrical devices are incorporating touchscreen type displays. A touchscreen is a display that detects the presence, location, and pressure of a touch within the display area, generally by a finger, hand, stylus, or other pointing device. The touchscreen enables a user to interact with the display panel directly without requiring any intermediate device, rather than indirectly with a mouse or touchpad. Touchscreens can be implemented in computers or as terminals to access networks. Touchscreens are commonly found in point-of-sale systems, automated teller machines (ATMs), mobile phones, personal digital assistants (PDAs), portable game consoles, satellite navigation devices, and information appliances.
There are a number of types of touchscreen technologies. A capacitive touch sensor includes multiple layers coated, partially coated, or patterned with a material that conducts a continuous electrical current. The sensor exhibits a precisely controlled field of stored electrons in both the horizontal and vertical axes to achieve capacitance. The human body is conductive; therefore, influences electric fields stored in a capacitance. When a reference capacitance of the sensor is altered by another capacitance field, such as a finger, electronic circuits located at each corner of the panel measure the resultant distortion in the reference capacitance. The measured information related to the touch event is sent to the controller for mathematical processing.
Capacitive touch sensors are typically formed using transparent conductors, such as ITO (Indium Tin Oxide) conductors, formed in layers. In an exemplary configuration, a first layer is positioned on top of a second layer. The second layer has bottom conductors that form drive electrodes, also referred to as drive lines, and the first layer has top conductors that form sense electrodes, also referred to as sense lines. Each cross-point of a drive line and a sense line forms a capacitor having a measured capacitance. The objective is to determine an estimate of a touch position on the capacitive touch sensor. When a finger, or other object that is grounded, is positioned on or proximate a cross-point of the sensor, there is a change in the measured capacitance at that cross-point.
Manufacturing of touchscreens having capacitive touch sensors requires proper alignment of the multiple layers both laterally and rotationally under high speed processing. Printed targets have been used for registering various assembly operations including layer lamination, laser cutting and excising. FIG. 1 illustrates a conventional printed target. Multiples of these targets are printed in strategic locations of each layer. Targets on each layer are aligned with targets on corresponding layers to form sets of aligned targets, each set including one target from each layer. The aligned targets are then punched by means of an aligning punch system such that a pin is punched through the layers at each set, thereby holding the layers in positioned according to the aligned targets.